Two to Three. Not counting Leatherman Squirt.
One everyday sort of knife. - Leek or Delica. Sometimes BM 921.
One a bit more heavier duty. - Mini Socom Elite or some small fixed.
One smaller knife. - Smith&Wesson Pocket Protector or Falkniven U2
Why carry more then one?
I began with one. Then one day, I thought, I might need something more durable. So I got another. That makes two knives.
One day, I saw little knife from S&W. I thought it's cute and it would fit in the watch pocket on my jean. I bought it. I found that it's easier to carry it around being clipped to belt loop. Easy to access. Good for small cutting. So, I began to carry three and used all three to good effect.
I try to maintain sort of variation. I try not to carry similar knives. Different knives for different job.
Yesterday, I got some unpleasant occurance happening twice. So, I thought, I might need something more durable than my regular heavy or tough knives. I'm carrying Strider DB today.
I recently got BM Rescue Hook. I'm carrying it, too. But I don't count it as a knife. You can't do what you normally do with knives with it.